Presidential candidates and sitting presidents should be required by law to publicly disclose their tax returns.

For four decades, candidates and sitting presidents have disclosed their tax returns, recognizing that public expectations for transparency demand no less. According to the Tax History Project’s research on presidential tax returns, every president of the United States since Jimmy Carter has disclosed at least one year of returns prior to taking office. Once presidents assume office, it has become common practice for them to release tax returns annually. The vast majority of their challengers have either matched or exceeded that standard.

Recent questions about when and whether candidates will publicly disclose their returns, however, have raised new doubts about the strength of our political norms. A detailed public view of candidates’ financial backgrounds can’t be taken for granted.

Congress can and should fix this. Just as presidential candidates are required to submit personal financial disclosure forms to the Federal Election Commission, they could be required to submit their tax returns for public review. An orderly, enforceable, rule-based process would let us skip the drama and doubts, and ensure access to what we already expect of our candidates: a reasonably clear view into their financial lives.

We shouldn’t be naive about privacy or the gravity of imposing mandatory disclosure requirements. Tax returns contain sensitive information. Americans still share a fundamentally private approach to personal finance and real estate. In much of the world, political opposition candidates face persecution from politically motivated law enforcement. Despite these concerns, declared American presidential candidates should be held to a higher standard of transparency. Tax return disclosure for presidential candidates can inform the public without creating a significant risk of abuse. Decades of experience have taught us that the finances of presidents and candidates are essential to our public understanding and political dialogue.

The public interest in tax return disclosure is only getting greater as candidates increasingly represent massive networks of corporate, nonprofit and political power. Complex tax arrangements that obfuscate ownership and influence have become the hallmark of concentrated financial power. The Panama Papers have recently underscored this point, as has an international summit this week on reining in corruption, which is very much a work in progress. This is even more pressing when one considers that the president is explicitly exempted from many of our conflict of interest laws.

This isn’t a one-line fix for Congress. Lawmakers will have to decide which agency should manage such a mandate and how to navigate pre-existing privacy protections. A useful precedent already exists, though: The Ethics in Government Act of 1978 established a disclosure system for senior officials. This law could be amended to include tax returns. Congress will also have to deal with questions about enforcement, accuracy, timing of disclosure and redaction standards.

These are relatively minor details, though. Decades of public expectations and reporting have clearly demonstrated that tax return disclosure helps inform voters before they head to the polls.

It’s time to put in place a rule-based process to protect our access to the information we’ve come to expect. The conduct of our presidential candidates and presidents can no longer be taken for granted.